The background description provided here is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.
Substrate processing systems for performing deposition and/or etching include a processing chamber with a pedestal. A substrate such as a semiconductor wafer may be arranged on the pedestal. For example in a chemical vapor deposition (CVD) process, a gas mixture including one or more precursors may be introduced into the processing chamber to deposit film on the substrate or to etch the substrate. In some substrate processing systems, plasma may be used to activate chemical reactions and is referred to herein as plasma enhanced CVD (PECVD).
Amorphous carbon and silicon films may be used as hardmasks for etching high aspect ratio features during substrate processing. For example in 3D memory applications, the hardmask film should be highly etch selective. As a result, the hardmask film should have higher modulus, denser, and more etch-chemistry-resistive bonding matrices. A balance is struck between being able to remove the hardmask film during an opening process and having high selectivity to the dielectric etching processes.
Tungsten carbide film is crystalline and is considered to be a hard coating. Tungsten carbide can act as a good hardmask film. However, tungsten carbide film is typically difficult to remove. Tungsten carbide film is usually deposited using deposition methods other than PECVD. While tungsten carbide film has been deposited using PECVD, very high process temperatures (approximately 800° C.) are used. For example, see “Plasma Enhanced Chemical Vapor Deposition Nanocrystalline Tungsten Carbide Thin Film and Its Electro-catalytic Activity”, H. Zheng et. al., Journal of Material Science Technologies, Vol. 21, No. 4 2005, pp 545-548. The higher processing temperatures used in PECVD are often unsuitable for many applications.